Particular requirements are placed on remote controls or telecontrols for items of industrial or agricultural equipment. On the one hand, rough service conditions preclude the use of filigree, easily contaminated plug-in contacts for charging or information transmission purposes; on the other hand, for safety reasons it must be possible for a remote control to be reliably and unambiguously assigned to a device. The accidental control and startup of an “external” unit could not only cause material damage by also endanger human life and health.